Editing Meteoroid (section)

=== In the Solar System ===
Most meteoroids come from the [[asteroid belt]], having been perturbed by the gravitational influences of planets, but others are particles from [[comet]]s, giving rise to [[meteor shower]]s. Some meteoroids are fragments from bodies such as Mars or the [[Moon]], that have been thrown into space by an impact.

Meteoroids travel around the Sun in a variety of orbits and at various velocities. The fastest move at about {{cvt|42|km/s|mph|}} through space in the vicinity of Earth's orbit. This is [[escape velocity]] from the Sun, equal to the square root of two times Earth's speed, and is the upper speed limit of objects in the vicinity of Earth, unless they come from interstellar space. Earth travels at about {{cvt|29.6|km/s|mph|}}, so when meteoroids meet the atmosphere head-on (which only occurs when meteors are in a [[retrograde orbit]] such as the [[Leonids]], which are associated with the retrograde comet [[55P/Tempel–Tuttle]]) the combined speed may reach about {{cvt|71|km/s|mph|}} (see [[Specific energy#Astrodynamics]]). Meteoroids moving through Earth's orbital space average about {{cvt|20|km/s|mph|}},<ref>{{cite journal |author=Interagency Group (Space) Working Group on Orbital Debris |title=Report on Orbital Debris |date=February 1989 |website=NASA Technical Reports Server |page=1 |url=https://ntrs.nasa.gov/citations/19900003319 |hdl=2060/19900003319 |access-date=2023-05-31 |archive-date=2023-05-31 |archive-url=https://web.archive.org/web/20230531171611/https://ntrs.nasa.gov/citations/19900003319 |url-status=dead}}</ref> but due to Earth's gravity meteors such as the [[Phoenicids]] can make atmospheric entry at as slow as about 11&nbsp;km/s.

On January 17, 2013, at 05:21 PST, a one-meter-sized comet from the [[Oort cloud]] entered Earth atmosphere over [[California]] and [[Nevada]].<ref name="CAMS"/> The object had a retrograde orbit with perihelion at 0.98&nbsp;±&nbsp;0.03&nbsp;[[Astronomical unit|AU]]. It approached from the direction of the constellation [[Virgo (constellation)|Virgo]] (which was in the south about 50° above the horizon at the time), and collided head-on with Earth's atmosphere at {{cvt|72|±|6|km/s|mph}}<ref name="CAMS">{{cite web |title=2013 January 17 Sierra Nevada fireball |publisher=[[SETI Institute]] |first=Peter |last=Jenniskens |author-link=Peter Jenniskens |url=http://cams.seti.org/index-archive3.html |access-date=2014-11-16}} | {{cite web |url=http://www.seti.org/seti-institute/news/earth-collides-with-comet |title=Earth Collides Head-On with Small Comet |publisher=[[SETI Institute]] |access-date=2013-01-25 |archive-date=2013-01-28 |archive-url=https://web.archive.org/web/20130128052127/http://www.seti.org/seti-institute/news/earth-collides-with-comet}}</ref> vaporising more than {{cvt|100|km|ft|-4}} above ground over a period of several seconds.